This invention relates to thermoplastic and thermosetting polymers which incorporate metal atoms; and to novel intermediates for preparing such polymers.
The metal containing resins of this invention are useful in a wide variety of applications, e.g., in the fabrication of composites, castings, as reimpregnation and/or laminating resins, and other uses usually found for organic resin systems. The presence of the metal atom in the basic resin molecule makes possible the formulation of resin matrix systems which are capable of absorbing large amounts of energy for specific related applications. The metal containing resins of this invention may also be carbonized or graphitized as hereinafter discussed.
In preparing high temperature, corrosion and ablative resistant structures, it is the practice to impregnate refractory materials with a synthetic resin, shape the structure to the desired form, and thereafter finally cure the resin at the necessary elevated temperatures. Useful resins used heretofore for this purpose have included, for example, phenolic resins, epoxy resins and the like. With the advent of aerospace products, the requirements for materials having suitable ablative characteristics have become even more critical and, accordingly, the presence of carbonized products has found particularly acceptable application in this field. Thus, in preparing such products, resin impregnated refractory materials such as silica, carbon and graphite fibers and fabrics have been heated at high temperatures in order to reduce the impregnated resins substantially to carbon. The resulting products have improved high temperature characteristics due to the carbonized matrix materials present therein. The properties of the resins used to impregnate and coat the refractory fiber materials must be such that during the pyrolysis outgasing problems are minimized with a substantial amount of the original resin material being retained in the form of carbon matrix in the product structure. Thus, resin products, which upon carbonization undergo extensive volatilization, will not only yield a product in which a substantial amount of the pyrolyzing resin matrix has been driven off, but there is the additional danger that outgasing may occur at such a rate and in such a manner that the integrity of the refractory fibers or cloth composite may be impaired. In addition, where a substantial portion of the resin has been decomposed during the carbonization, a weakened structure may also result.
U.S. Pat. No. 3,544,530 discloses synthetic resins prepared by polymerizing furfuryl alcohol with an ester prepolymer of maleic acid or anhydride and a polyhydric alcohol. These copolymers, when pyrolyzed at high temperatures, retain a substantial amount of the original resin weight. Accordingly, these copolymers are valuable in preparing carbonized, high temperature, corrosion resistant and ablative products. The disclosure of this patent is incorporated herein by reference.